// HTMLParser Library - A java-based parser for HTML
// http://htmlparser.org
// Copyright (C) 2006 Derrick Oswald
//
// Revision Control Information
//
// $URL: https://svn.sourceforge.net/svnroot/htmlparser/trunk/parser/src/main/java/org/htmlparser/filters/NotFilter.java $
// $Author: derrickoswald $
// $Date: 2006-09-16 10:44:17 -0400 (Sat, 16 Sep 2006) $
// $Revision: 4 $
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the Common Public License; either
// version 1.0 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// Common Public License for more details.
//
// You should have received a copy of the Common Public License
// along with this library; if not, the license is available from
// the Open Source Initiative (OSI) website:
//   http://opensource.org/licenses/cpl1.0.php

package org.htmlparser.filters;

import org.htmlparser.Node;
import org.htmlparser.NodeFilter;

/**
 * Accepts all nodes not acceptable to it's predicate filter.
 */
public class NotFilter implements NodeFilter {
	/**
	 * The filter to gainsay.
	 */
	protected NodeFilter mPredicate;

	/**
	 * Creates a new instance of a NotFilter. With no predicates, this would
	 * always return <code>false</code> from {@link #accept}.
	 * 
	 * @see #setPredicate
	 */
	public NotFilter() {
		setPredicate(null);
	}

	/**
	 * Creates a NotFilter that accepts nodes not acceptable to the predicate.
	 * 
	 * @param predicate
	 *            The filter to consult.
	 */
	public NotFilter(NodeFilter predicate) {
		setPredicate(predicate);
	}

	/**
	 * Get the predicate used by this NotFilter.
	 * 
	 * @return The predicate currently in use.
	 */
	public NodeFilter getPredicate() {
		return (mPredicate);
	}

	/**
	 * Set the predicate for this NotFilter.
	 * 
	 * @param predicate
	 *            The predidcate to use in {@link #accept}.
	 */
	public void setPredicate(NodeFilter predicate) {
		mPredicate = predicate;
	}

	//
	// NodeFilter interface
	//

	/**
	 * Accept nodes that are not acceptable to the predicate filter.
	 * 
	 * @param node
	 *            The node to check.
	 * @return <code>true</code> if the node is not acceptable to the
	 *         predicate filter, <code>false</code> otherwise.
	 */
	public boolean accept(Node node) {
		return ((null != mPredicate) && !mPredicate.accept(node));
	}
}
